There is evidence that the use of mammographic screening is relatively low among socioeconomically disadvantaged and minority women. In-reach activities, which use contacts with the health care system to educate and motivate patients, have considerable potential for increasing mammography completion rates. The overall aim of the proposed research is to increase screening mammography participation by women from hard-to-reach groups through a clinic-based intervention program. Specific study objectives are to obtain information about the screening behavior of disadvantaged women; develop, implement, and evaluate the effect of a mammography program; and assess the costs of intervention activities. The setting for the study will be the Adult Medicine Clinic of Seattle's Harborview Medical Center. Subjects for the study will be women aged 50-69 who visit the clinic during an 18-month period. The intervention pro gram will be guided by a comprehensive theoretical framework that addresses both environmental and individual considerations. Attention will be given to organization of the clinic through implementation of patient tracking and provider reminder systems; and education of physicians and clinic staff. The Theory of Reasoned Action, as well as quantitative and qualitative data collection methods, will be used to understand the target population's screening behavior and to guide the development of patient intervention activities. These will include use of audio-visual and print education materials; physician reinforcement of mammography; transportation assistance; pre-appointment reminders; and telephone follow-up if appointments are missed. A randomized controlled trial employing "Firm System" research methodology will be employed to evaluate the effect of the intervention program on mammography participation. The study sample will include a minimum of 140 experimental and 280 control women who will have previously been individually randomized to one of three equivalent group practices. The outcome variable of interest will be mammography completion within three months of initial exposure to the intervention program. Costs of the intervention program will be systematically assessed.